All 6 questions from the West African Examinations Council (WAEC) Biology 2022 Theory paper, with the correct answer and a full explanation for each. Free, no signup needed.
1(a)(i) What is a cell?
(ii) Name three scientists that are associated with the discovery of the cell.
(b)(i) Make a diagram, 6cm to 8cm long of a plant cell and label only the organelle responsible for cell reproduction.
(ii) Name one blood cell in humans that does not have the organelle in 1b(i).
(iii) What is the biological implication of the cell named 1b(ii) not possessing the organelle responsible for cell reproduction?
(c) List six organelles found in a plant cell.
Model answer
(a)(i) The cell is the basic, structural and functional unit of life.
(ii) Scientists associated with the discovery of the cell: Theodor Schwann; Matthias Schleiden; Rudolf Virchow.
(b)(i) [Diagram: plant cell labelled, showing cell wall, cell membrane, nucleus (labelled as the organelle responsible for cell reproduction), cytoplasm, chloroplast, vacuole, endoplasmic reticulum, Golgi apparatus, mitochondria.]
NB: The key organelle responsible for cell reproduction is the nucleus.
(ii) The blood cell that lacks a nucleus is the red blood cell/erythrocyte.
(iii) The absence of a nucleus allows the red blood cell to contain more haemoglobin and, therefore, carry more oxygen molecules. However, without a nucleus, they cannot divide to make new red blood cells.
(c) Organelles found in a plant cell: Nucleus; Mitochondria; Chloroplast; Vacuole; Endoplasmic reticulum; Golgi apparatus; Lysosome; Cell wall.
2(a) Complete the table by ticking (✓) the appropriate group to which each of the listed elements required by plants belongs (microelement or macroelement): Hydrogen, Copper, Magnesium, Zinc, Phosphorus, Manganese, Boron, Nitrogen, Carbon, Oxygen.
(b) State: (i) three differences between the dentition of a herbivore and a carnivore; (ii) four differences between the dentition of a human and a goat.
(c) What are milk teeth?
Model answer
(a) Completed table:
Macroelements: Hydrogen, Magnesium, Phosphorus, Nitrogen, Carbon, Oxygen.
Microelements: Copper, Zinc, Manganese, Boron.
(b)(i) Differences between dentition of herbivore and carnivore:
Herbivore | Carnivore
- Teeth suited to cutting, gnawing and biting | Teeth suited to catching, killing and tearing the prey
- Lack canine teeth | Have canine teeth
- Have diastema | Lack diastema
- Have flat teeth | Have pointed teeth
(ii) Differences between dentition of human and goat:
Human | Goat
- Lack diastema | Have diastema
- Have canine | Lack canine
- Have incisors on both upper and lower jaws | Lack incisors on the upper jaw (only have on the lower jaw)
- Have dental pads | Lack dental pads
(c) Milk teeth are the first set of teeth in the growth and development of humans. These teeth are twenty in number. They are later replaced by the permanent teeth.
3(a)(i) What is the ecological niche of an organism?
(ii) State five roles played by a mango tree in its ecological niche.
(b)(i) State two reasons why ecologists use sampling techniques in population studies.
(ii) State four examples of sampling techniques used in population studies.
(c) Name four types of fingerprints in humans.
Model answer
(a)(i) The ecological niche is the position or function of an organism in a habitat. It describes how a species interacts within an ecosystem.
(ii) Roles played by a mango tree in its ecological niche: It provides fruit; It provides firewood; It provides organic matter for soil replenishment; It enhances soil conservation; It has many medicinal applications.
(b)(i) Reasons ecologists use sampling techniques: It saves time; It is usually impossible to go and count each species present, hence the need for sampling techniques.
(ii) Examples of sampling techniques: Random sampling; Systematic sampling; Convenience sampling; Cluster sampling; Stratified sampling.
(c) Types of fingerprints in humans: Arch; Loop; Whorl; Compound.
4(a)(i) What are conservation laws?
(ii) State three conservation laws.
(b)(i) State two reasons why animals are poached.
(ii) Name five animals that are commonly poached.
(c) State four effects of excessive use of the forest.
(d) Explain briefly the following terms: (i) blood transfusion; (ii) antigen.
Model answer
(a)(i) A conservation law states that a particular parameter of a system does not change as the system evolves over time.
(ii) Conservation laws: Law of conservation of matter; Law of conservation of energy.
(b)(i) Reasons animals are poached: Food requirement/for adventure; Medicinal values of some animal parts; Cultural and religion's views.
(ii) Animals commonly poached: Tigers; Rhinos; Gorillas; Elephants; Sea turtles; Amur leopard; African pangolins.
(c) Effects of excessive use of the forest: Habitat destruction of wild animals; Climate change; Desertification; Soil erosion; Flooding.
(d)(i) Blood transfusion is the transfer of blood or a blood component from one healthy person (a donor) to a sick person (a recipient).
(ii) An antigen is a molecule that initiates the production of an antibody and causes an immune response.
5(a)(i) State three differences between the alimentary canals of earthworm and cockroach.
(ii) State three similarities between the alimentary canals of earthworm and cockroach.
(b) The diagram below is an illustration of a biological cycle (the water cycle). Study it and answer questions 5(b)(i) to 5(b)(iii):
(i) Name the biological cycle.
(ii) Explain briefly three roles played by plants and animals in the cycle.
(iii) Name the processes that occur in X, Y and Z.
Model answer
(a)(i) Differences between alimentary canals of earthworm and cockroach:
Earthworm | Cockroach
- The digestive tract is straight and simple | The digestive tract is curved and more developed
- It lacks crop | It has crop
- It lacks colon | It has colon
(ii) Similarities between alimentary canals of earthworm and cockroach:
- They both have gizzard.
- They both have pharynx.
- They both have oesophagus.
(b)(i) The biological cycle illustrated is the water cycle.
(ii) Roles played by plants and animals in the water cycle: Plants contribute to the water cycle via transpiration; Animals release water into the water cycle when they exhale; Water is also a product of respiration in plants; Animals also contribute to the water cycle through excretion of waste.
(iii) X represents condensation; Y represents evaporation; Z represents run-off/respiration (per the diagram's labelling).
6. Study specimens H, K, L and M and answer questions 6(a) to 6(f).
(a) State two observable structural differences between: (i) specimens H and L; (ii) specimens K and M.
(b) State two ways each by which specimens H and M adapt to their modes of life.
(c) Make a drawing, 8cm to 10cm long of specimen M and label fully.
(d) Name one habitat of the organism that possesses specimen K.
(e) Name one feeding habit of each of the organisms that possess specimens H and L.
(f) State two observable similarities between specimens H and L.
Model answer
(a)(i) Observable structural differences between specimens H and L (based on ear/appendage type descriptions): 'I' refers to the ear ossicles — these bones are reputed as the smallest bones in the body. They are three in number: Malleus (Hammer); Incus (Anvil); Stapes (Stirrup).
(ii) Observable structural differences between specimens K and M (webbed feet vs claws): K has no webbed feet with long and curved claws; M has webbed feet with short and flattened claws.
(b) Adaptations: H has a sharp pointed beak for picking food, and has eyes for sight; M has webbed feet for swimming.
(c) [Drawing of specimen M, 8-10cm long, fully labelled with beak, webbed feet, and relevant body parts.]
(d) The organism possessing specimen K has a terrestrial habitat.
(e) Feeding habits: H is heterotrophic (or holozoic); L exhibits filter feeding.
(f) Similarities between H and L: They both have beaks; They both possess eyes.
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